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Retirement Plans (Narrative) (Details) - USD ($) $ in Millions | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 | Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |
Payment for Pension and Other Postretirement Benefits |  |  | $ 0.7 |  |  |
Defined Benefit Plan, Amortization of Gain (Loss) |  |  | (1.9) | $ (3.2) | $ (4.0) |
Defined Benefit Plan, Plan Assets, Contributions by Employer |  |  | 0.6 | 0.0 |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment |  |  | (0.7) | 0.0 | 0.0 |
Payment for Pension Benefits |  |  | $ 0.7 | $ 0.0 | $ 35.0 |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate |  |  | 3.26% | 4.37% | 3.88% |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  |  | 100.00% |  |  |
Discount rate |  |  | 4.37% | 3.88% | 3.68% |
Defined Contribution Plan, Cost |  |  | $ 5.5 | $ 4.7 | $ 4.1 |
Minimum [Member] |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |
Defined Benefit Plan Expected Return on Plan Assets Major Asset Classes Time Horizon |  |  | 10 |  |  |
Maximum [Member] |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |
Defined Benefit Plan Expected Return on Plan Assets Major Asset Classes Time Horizon |  |  | 15 years |  |  |
Equity Securities [Member] |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  |  | 20.00% |  |  | 30.00%
Equity Securities [Member] | Minimum [Member] |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  |  | 15.00% |  |  |
Forecast [Member] |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |
Defined Benefit Plan, Amortization of Gain (Loss) |  | $ (2.8) |  |  |  |
Multiemployer Plans, Pension [Member] |  |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |  |
Payment for Pension and Other Postretirement Benefits | $ 0.4 |  |  |  |  |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment |  |  | $ 1.1 |  |  |

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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Amount of contribution received by defined benefit plan from employer which increases plan assets. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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- Definition Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(i) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 + Details
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